Because an optical power source cable is close to a detector cable in the kappa measurement, for example, the fibers of the suspension have to be separate. Flocks, which easily form, cause noise-like variation in the optical signal which deteriorates the reliability of the measurement results.
The problem has been mitigated by increasing a measurement period and averaging the results over the measurement period. This kind of integration over time makes the measurement very slow. Hence, there is a need to improve the measurements.